How do things look with 101K?

Petey

Original poster
Member
Aug 27, 2012
105
One thing I have never really learned to do was read plugs.

cyl 1 is on the right, 6 is on the left

20180428_151346.jpg20180428_151232.jpg
 

Reprise

Lifetime VIP Donor
Supporting Donor
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Jul 22, 2015
2,724
Those look pretty good to me, at least. Worst one of the bunch is 5, and even it's not terrible. That light tan color is what you want to see, and your center / side electrodes don't look bad, either (you don't want to see those too worn away / damaged; you'll have a little bit of wear in 100K mi, to be sure)

Make sure you replace them w/ the ACDelco iridiums (41-103, IIRC) - and do *not* gap the plug - they're pre-gapped, and you can easily damage / break the iridium electrode if you try adjusting the gap. FWIW, I checked the gap on all eight of my 110s, and all eight were on the money.

A little anti-seize on the threads would be good, and if you've got a torque wrench, I'm pretty sure they go in at 13 ft/lb on the 4200.

Keep an eye on #5 going forward - the cowl drips water right on top of it, and it can cause problems when water collects in the plug well.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Keep an eye on #5 going forward - the cowl drips water right on top of it, and it can cause problems when water collects in the plug well.

That would actually be #4 that has water problems from the cowl.

Those are in good shape as @Reprise indicated. I can't even tell a difference with #5 except maybe more shadow on the porcelain. There isn't even any oil or rust marks on the exterior which would indicate valve cover/plug well leaks. How many miles on these?
 

Petey

Original poster
Member
Aug 27, 2012
105
That would actually be #4 that has water problems from the cowl.

Those are in good shape as @Reprise indicated. I can't even tell a difference with #5 except maybe more shadow on the porcelain. There isn't even any oil or rust marks on the exterior which would indicate valve cover/plug well leaks. How many miles on these?
100K, original plugs

doesn't really idle

Mostly highway
 

christo829

Member
Dec 7, 2011
497
Fairfax, Virginia
I'll third that those just look worn, but not abnormal. Looks like there's some buildup on the side electrode,
but again, not abnormal. If you saw something like a baked on black coating, white buildup, or chipped
insulation that would be indicative of a problem, but that more even tan color is about what you should expect
on those plugs with that mileage.

Could you provide a little more detail about it not really idling? Did you clean
the throttle body (and disconnect the battery when you did)? That might be interfering with your idle. The
old plugs might have been idling poorly just from electrode erosion slowly altering the gap.

Cheers-

Chris
 

Petey

Original poster
Member
Aug 27, 2012
105
I'll third that those just look worn, but not abnormal. Looks like there's some buildup on the side electrode,
but again, not abnormal. If you saw something like a baked on black coating, white buildup, or chipped
insulation that would be indicative of a problem, but that more even tan color is about what you should expect
on those plugs with that mileage.

Could you provide a little more detail about it not really idling? Did you clean
the throttle body (and disconnect the battery when you did)? That might be interfering with your idle. The
old plugs might have been idling poorly just from electrode erosion slowly altering the gap.

Cheers-

Chris
woops sorry for the confusion.

it idles fine , I meant it does not have a lot of idling time.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I should have clued in with that part number on them. Those were original, no longer available. Time to replace them at that mileage. Now it's ACDelco 41-103, which are the only ones that this engine likes. Others have been proven to make the engine barf.
 

Reprise

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Supporting Donor
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Jul 22, 2015
2,724
I'll second the ac delco - when I got the Envoy, it had a slightly rough idle - too much so to be a 'LS-type' roughness (the LS isn't known for a glass-smooth idle 100% of the time...some days are better than others - but there are no misfires per the PCM. For a 15yr old motor, I'll take it without complaint)

Anywhoo...Got a set of the ac delco, and when I removed the old ones, they were practically new. They were Bosch Iridiums, as well - so in theory, all should have been well. But it wasnt - the truck idles much more smoothly with the Delco plugs. Made a believer out of me.

My #1 was a little black around the bottom rim when I took it out. I should check the Delco plug, now that it has a few months / miles on it. But since it's the hardest (for me) to remove, it's not something that warrants a lot of priority from me, tbh.
 

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